Prince William Breaks Ice with Harry by Wishing Archie Happy Birthday

A simple birthday wish has royal implications, because Prince William has reached out across the pond to wish the son of his estranged brother a happy birthday.

Meghan and Harry's son, Archie, turns 3 Friday, and William and Kate marked the occasion with a photo of the royal fam -- which includes Archie -- with the caption, "Wishing Archie a very happy 3rd Birthday today."

It's hugely significant ... as we reported, Harry flew back to England last month and met with the Queen and Charles, but not William. The 2 have been estranged for several years now, and the Oprah interview seemed to cement their estrangement.

Archie's 7th in line to the thrown. He hasn't been in the U.K. since Fall, 2019, when Meghan and Harry took him to Canada and shortly thereafter settled in Montecito, near Santa Barbara.

Harry said recently he considers Montecito his home, not England.